The T(4;11) Fusion Protein MLL/AF4 Regulates TERT Expression

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3111-3111
Author(s):  
Andreas Gessner ◽  
Maria Thomas ◽  
Patricia Garrido Castro ◽  
Olaf Heidenreich ◽  
Johann Greil
Keyword(s):  
Cell Lines ◽  
Molecular Mechanisms ◽  
Fusion Transcript ◽  
Telomerase Activity ◽  
Small Interfering Rnas ◽  
Inhibition Of Proliferation ◽  
Knock Down ◽  
Protein Levels ◽  
Induced Apoptosis ◽  
Tert Expression

Abstract About 50% of all infants suffering from acute lymphoblastic leukaemia (ALL) show the translocation t(4;11)(q21;q23) which creates the fusion genes MLL/AF4 and AF4/MLL. This reciprocal translocation identifies a therapy resistant form of leukaemia with a poor prognosis. In order to gain a better insight into the molecular mechanisms of t(4;11) leukaemias we used the two ALL cell lines SEM and RS4;11, both harbouring the t(4;11) translocation, however with different fusion sites. Specific small interfering RNAs (siRNAs) against the two fusion site variants of the MLL/AF4 fusion transcript were designed and transfected into the respective cells via electroporation, using very mild conditions. Serial electroporations at two-day intervals resulted in sustained depletion of the MLL/AF4 transcript up to 70–80%, and depending on the experimental setup, cells were analysed after two or three electroporations. Knock-down of MLL/AF4 resulted in strong inhibition of proliferation and clonogenicity in the two t(4;11)-positive cell lines SEM and RS4;11, along with induction of apoptosis. MLL/AF4 depletion resulted in a 65% decrease in telomerase activity in both SEM and RS4;11 cells, with telomerase reverse transcriptase (TERT) expression being reduced twofold on both transcript and protein levels. Notably, TERT reduction was even stronger (90% depletion) when apoptosis caused by MLL/AF4 knock-down was suppressed with the caspase inhibitor zVAD. In contrast, levels of the RNA component of the telomerase, TERC, were not affected by MLL/AF4 knock-down. Additionally, MLL/AF4 knock-down was associated with reduced expression of several members of the HOXA gene cluster, HOXA6 (65% reduction), HOXA7 (85% reduction), HOXA9 (60% reduction) and HOXA10 (75% reduction). Interestingly, siRNA-mediated knock-down of the MLL/AF4 target gene HOXA7 also induced apoptosis and resulted in a 70% decrease of TERT levels in two t(4;11) positive cell lines without affecting MLL/AF4. Chromatin immunoprecipitation assays revealed HOXA7 binding to the promoter of TERT. Therefore, MLL/AF4 regulates TERT expression, at least in part, via HOXA7. These data suggest that t(4;11) positive cells with substantially lower TERT expression undergo apoptosis, and that TERT may play an antiapoptotic role in t(4;11) positive ALL. Furthermore, these studies identify TERT as a putative new therapeutic target in this therapy-resistant infant leukaemia.

Inhibition of miR-182-5p protects cardiomyocytes from hypoxia-induced apoptosis by targeting CIAPIN1

2018 ◽  
Vol 96 (5) ◽  
pp. 646-654 ◽  
Author(s):  
Yunsong Zhang ◽  
Jun Fang ◽  
Huiwen Ma
Keyword(s):  
Molecular Mechanisms ◽  
Annexin V ◽  
Bioinformatic Analysis ◽  
Luciferase Reporter ◽  
Protective Effects ◽  
Small Interfering Rnas ◽  
Protein Levels ◽  
Hypoxic Conditions ◽  
Induced Apoptosis ◽  
Apoptosis Inhibitor

Myocardial infarction (MI), a type of ischemic heart disease, is generally accompanied by apoptosis of cardiomyocytes. MicroRNAs play the vital roles in the development and physiology of MI. Here, we established a downregulation model of miR-182-5p in H9c2 cells under hypoxic conditions to investigate the potential molecular mechanisms for miR-182-5p in hypoxia-induced cardiomyocyte apoptosis (HICA). RT-qPCR indicated that miR-182-5p levels exhibit a time-dependent increase in the rate of apoptosis induced by hypoxia. The results from the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and LDH (lactate dehydrogenase) assays indicated that cardiomyocyte injury noticeably increased after exposure to hypoxia. Meanwhile, hypoxia dramatically increased the apoptosis rate [which was reflected in the results from the annexin V – propidium iodide (PI) assay], enhanced caspase-3 activity, and reduced the expression of Bcl-2. Downregulation of miR-182-5p can significantly reverse hypoxia-induced cardiomyocyte injury or apoptosis. Importantly, bioinformatic analysis and dual-luciferase reporter assay revealed that CIAPIN1 (cytokine-induced apoptosis inhibitor 1) was a direct functional target of miR-182-5p, and that inhibition of miR-182-5p can lead to an increase in CIAPIN1 expression at both the mRNA and protein levels. Furthermore, the knockdown of CIAPIN1 with small interfering RNAs (siRNAs) efficiently abolished the protective effects of miR-182-5p inhibitor on HICA, demonstrating that miR-182-5p plays a pro-apoptotic role in cardiomyocytes under hypoxic conditions by downregulating CIAPIN1. Collectively, our results demonstrate that miR-182-5p may serve an underlying target to prevent cardiomyocytes from hypoxia-induced injury or apoptosis.

Bortezomib blocks Bax degradation in malignant B cells during treatment with TRAIL

Blood ◽  
2008 ◽  
Vol 111 (5) ◽  
pp. 2797-2805 ◽  
Author(s):  
Feng-Ting Liu ◽  
Samir G. Agrawal ◽  
John G. Gribben ◽  
Hongtao Ye ◽  
Ming-Qing Du ◽  
...  
Keyword(s):  
B Cells ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Resistant Cell ◽  
Protein Levels ◽  
Bax Protein ◽  
Degradation Activity ◽  
Potent Drug ◽  
Induced Apoptosis

Proapoptotic Bcl-2 family member Bax is a crucial protein in the induction of apoptosis, and its activation is required for this process. Here we report that Bax is a short-lived protein in malignant B cells and Bax protein levels decreased rapidly when protein synthesis was blocked. Malignant B cells were relatively resistant to tumor necrosis factor–related apoptosis inducing ligand (TRAIL)–induced apoptosis, and this correlated with low basal Bax protein levels. Furthermore, during treatment with TRAIL, the resistant cell lines showed prominent Bax degradation activity. This degradation activity was localized to mitochondrial Bax and could be prevented by truncated Bid, a BH3-only protein; in contrast, cytosolic Bax was relatively stable. The proteasome inhibitor bortezomib is a potent drug in inducing apoptosis in vitro in malignant B-cell lines and primary chronic lymphocytic leukemic (CLL) cells. In CLL cells, bortezomib induced Bax accumulation, translocation to mitochondria, conformational change, and oligomerization. Accumulation and stabilization of Bax protein by bortezomib-sensitized malignant B cells to TRAIL-induced apoptosis. This study reveals that Bax instability confers resistance to TRAIL, which can be reversed by Bax stabilization with a proteasome inhibitor.

scholarly journals 2193

2017 ◽  
Vol 1 (S1) ◽  
pp. 58-59
Author(s):  
Houda Alachkar ◽  
Martin Mutonga ◽  
Amanda de Albuquerque ◽  
Rucha Deo ◽  
Gregory Malnassy ◽  
...  
Keyword(s):  
Cell Viability ◽  
Cell Lines ◽  
Therapeutic Target ◽  
Leucine Zipper ◽  
Lymphoblastic Leukemia ◽  
Annexin V ◽  
Hematologic Malignancies ◽  
Cytotoxic Activities ◽  
Knock Down ◽  
Protein Levels

OBJECTIVES/SPECIFIC AIMS: Unlike the high cure rates (90%) of children with acute lymphoblastic leukemia (ALL), that of adults is still lagging behind and better therapies are needed. Maternal embryonic leucine-zipper kinase (MELK) is aberrantly upregulated in cancer, and implicated in cancer stem cell survival. A recent study has identified FOXM1, a MELK substrate, as a therapeutic target in B cell ALL (B-ALL). Thus, we hypothesized that MELK may act as a therapeutic target in ALL via targeting FOXM1 activity. METHODS/STUDY POPULATION: Western blot and qPCR were used to assess MELK expression in 14 ALL cell lines. Knock-down and kinase inhibition approaches targeting MELK expression and function, followed by CCK-8 and Annexin V (flow cytometry) assays to measure cell viability and apoptosis, respectively. RESULTS/ANTICIPATED RESULTS: MELK was significantly upregulated in patients with ALL (oncomine data analysis). MELK was also significantly higher in B-ALL and T-ALL cell lines compared with that in blood cells of healthy donors. MELK knock-down significantly decreased cell viability (40%–70%, p<0.05, Fig. 1) in ALL cells, and induced apoptosis (~40%). OTS167, a potent MELK inhibitor exhibited cytotoxic activities in both B and T-ALL cells. The IC50 of OTS167 ranged from 20 to 60 nM; we also found a significant increase in apoptosis (p<0.05). Mechanistically, MELK inhibition resulted in decrease of FOXM1 protein levels 3 hours post-treatment. DISCUSSION/SIGNIFICANCE OF IMPACT: MELK is highly expressed in ALL and represents a novel therapeutic target likely via modulating FOXM1 activity. Functional and mechanistic studies will complement and ensure the success of the undergoing Phase I/II clinical trial of OTS167 in patients with refractory or relapsed AML, ALL, and other advanced hematologic malignancies.

scholarly journals TIMP-2 regulates proliferation, invasion and STAT3-mediated cancer stem cell-dependent chemoresistance in ovarian cancer cells

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ruth M. Escalona ◽  
Maree Bilandzic ◽  
Patrick Western ◽  
Elif Kadife ◽  
George Kannourakis ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cell Lines ◽  
Cancer Progression ◽  
Mrna Level ◽  
Tissue Inhibitors Of Metalloproteinases ◽  
Ovarian Cancer Cells ◽  
Knock Down ◽  
Protein Levels ◽  
Response To Chemotherapy

Abstract Background The metzincin family of metalloproteinases and the tissue inhibitors of metalloproteinases (TIMPs) are essential proteins required for biological processes during cancer progression. This study aimed to determine the role of TIMP-2 in ovarian cancer progression and chemoresistance by reducing TIMP-2 expression in vitro in Fallopian tube secretory epithelial (FT282) and ovarian cancer (JHOS2 and OVCAR4) cell lines. Methods FT282, JHOS2 and OVCAR4 cells were transiently transfected with either single or pooled TIMP-2 siRNAs. The expression of different genes after TIMP-2 knock down (T2-KD) or in response to chemotherapy was determined at the mRNA level by quantitative real time PCR (qRT-PCR) and at the protein level by immunofluorescence. Sensitivity of the cell lines in response to chemotherapy after TIMP-2 knock down was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-Ethynyl-2′-deoxyuridine (EdU) assays. Cell invasion in response to TIMP-2 knockdown was determined by xCELLigence. Results Sixty to 90 % knock down of TIMP-2 expression was confirmed in FT282, OVCAR4 and JHOS2 cell lines at the mRNA and protein levels. TIMP-2 knock down did not change the mRNA expression of TIMP-1 or TIMP-3. However, a significant downregulation of MMP-2 in T2-KD cells occurred at both the protein and activation levels, compared to Control (Cont; scrambled siRNA) and Parental cells (P, transfection reagent only). In contrast, membrane bound MT1-MMP protein levels were significantly upregulated in T2-KD compared to Cont and P cells. T2-KD cells exhibited enhanced proliferation and increased sensitivity to cisplatin and paclitaxel treatments. Enhanced invasion was observed in the T2-KD-JOSH2 and OVCAR4 cells but not in T2-KD-FT282 cells. Treatment with cisplatin or paclitaxel significantly elevated the expression of TIMP-2 in Cont cells but not in T2-KD cells, consistent with significantly elevated expression of chemoresistance and CSC markers and activation of STAT3. Furthermore, a potent inhibitor of STAT3 activation, Momelotinib, suppressed chemotherapy-induced activation of P-STAT3 in OVCAR4 cells with concomitant reductions in the expression of chemoresistance genes and CSC markers. Conclusions The above results suggest that TIMP-2 may have a novel role in ovarian cancer proliferation, invasion and chemoresistance.

Adenosine A2A and Beta-2 Adrenergic Receptor Agonism: Novel Selective and Synergistic Multiple Myeloma Targets Discovered through Systematic Combination Screening

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 384-384
Author(s):  
Richard J. Rickles ◽  
Laura Pierce ◽  
Thomas Giordano ◽  
Winnie F. Tam ◽  
William Avery ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
High Throughput ◽  
Adrenergic Receptor ◽  
Molecular Mechanisms ◽  
Single Agent ◽  
Inhibition Of Proliferation ◽  
Cgs 21680 ◽  
Beta 2 ◽  
Adenosine A2a

Abstract Using a high throughput combination screening strategy, we have discovered that agonism of either adenosine A2A receptors (A2A) or beta-2 adrenergic receptors (bAR) demonstrate significant, synergistic, anti-proliferative effects in preclinical Multiple Myeloma (MM) models. Using quantitative synergy analysis, we observe that A2A and bAR agonists have significant anti-proliferative effects in a broad panel of 10 MM cell lines when combined with each other or with standard MM agents. Individual A2A agonists CGS-21680 and HE-NECA inhibited proliferation 25–80% with EC50s ranging from 2–20 nM. Individual bAR agonists salmeterol and formoterol inhibited proliferation 35–75% with EC50s ranging from 10–30 pM. Potent, highly synergistic, inhibition of proliferation, up to 95%, was demonstrated with combinations of A2A or bAR agonists and multiple agents including dexamethasone, lenalidomide, bortezomib, melphalan, doxorubicin, HDAC inhibitors and HSP90 inhibitors at clinically relevant concentrations. These combinations exceeded Loewe additivity, and demonstrated both substantial increases in efficacy over maximal single agent levels as well as significant potency shifting with many combination indices (CIs) in the range of 0.1 to 0.3. Synergistic anti-proliferative effects were observed broadly across several MM cell lines and when using cell lines unresponsive to standard MM drugs, e.g. A2A agonists CGS-21680 and HE-NECA in combination with dexamethasone inhibited 75–85% of the proliferation of EJM, and MOLP-8 dexamethasone-insensitive cell lines as compared to 35–60% for the single agent A2A agonists. The selective A2A antagonist SCH58261 but not A1, A2B and A3 selective antagonists DPCPX, MRS1754 and MRS1523 blocked the synergy and antiproliferative activity of HE-NECA, demonstrating that the effect is mediated via the A2A receptor. siRNA directed against adenosine and adrenergic receptor isoforms, caused a concomitant reduction in the antiproliferative effects of HE-NECA and salmeterol. Synergy (CI&lt;0.4) observed between A2A and bAR agonists suggested that while both these targets signal through Gs coupled signaling pathways, the two targets contribute to the antiproliferative effect via distinct molecular mechanisms. Anti-proliferative effects occurred through a synergistic induction of apoptosis. Combinations of either agonist with dexamethasone demonstrate 50–75% Annexin V positive MM.1S cells after 24 hours treatment whereas single agents show less than 10%. The activity, synergy and selectivity of A2A and bAR combinations were observed in xenograft models of MM. SCID CB17 mice received subcutaneous inoculation of RPMI-8226 cells and once tumors were palpable, mice were treated with vehicle, bortezomib (0.5 mg/kg IV Q3D), salmeterol (10 mg/kg s.c QD) or the combination of both agents. After 19 days of treatment, the combination showed significantly greater reduction in tumor volume than either of the single agents alone (70% vs. 34%; p&lt;0.05, ANOVA). High throughput combination screening facilitated the discovery of two novel and related classes of drug targets with highly synergistic and selective anti-tumor activity in MM. These preclinical data provide a strong rationale for the investigation of A2A and bAR agonists in the treatment of MM.

ARNT Mediates Chemotherapy Resistance by Modulating the Response to Oxidative Stress in AML Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2737-2737
Author(s):  
Richard A. Wells ◽  
Chunhong Gu ◽  
Joelle dela Paz
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Cell Lines ◽  
Akt Signaling ◽  
Mrna Levels ◽  
Antioxidant Genes ◽  
Protein Levels ◽  
Exogenous Expression ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

Abstract Abstract 2737 Poster Board II-713 Background Although patients with acute myelogenous leukaemia (AML) typically respond well to initial therapy, with over 75% of patients achieving complete remission, in the great majority the disease ultimately relapses. This is thought to be due to the inherent resistance of leukaemia stem cells to the effects of chemotherapy. While some mechanisms of chemoresistance, e.g. TP53 mutation and upregulation of P-glycoprotein expression, have been well characterized, this phenomenon remains incompletely understood and is a significant barrier to improving patient outcomes. Methods and results The thiazolidindione drug troglitazone (TG) induces apoptosis in AML cells via generation of intracellular reactive oxygen species (ROS), but the degree of sensitivity to TG is highly heterogeneous among AML cell lines. We studied expression of the transcription factor ARNT (aryl hydrocarbon nuclear translocator) in TG-sensitive and TG-resistant AML cell lines following TG treatment. In HL-60 cells, which are highly sensitive to induction of apoptosis by TG, ARNT mRNA levels remained constant following TG treatment and ARNT protein levels markedly decreased, while in U937 cells, which are TG resistant, ARNT mRNA levels increased and ARNT protein levels remained constant. We then tested the effect of exogenous expression of ARNT on the sensitivity of HL-60 cells to TG-induced apoptosis. HL-60 cells transduced with a retrovirus expressing ARNT became TG-resistant. Exogenous expression of ARNT also conferred resistance to induction of apoptosis by hydrogen peroxide, daunorubicin and etoposide. The cellular response to oxidative stress is governed by intracellular signaling pathways and through a transcriptional response through which expression of antioxidant genes is coordinated. HL-60 cells expressing ARNT had striking constitutive activation of AKT signaling, and treatment of these cells with a specific inhibitor of AKT signaling reversed their resistance to TG-induced apoptosis. The activation of AKT signaling by ARNT appears to be mediated by downregulation of expression of PP2A and alpha4, two key negative regulators of AKT phosphorylation. In addition, ARNT-transduced HL-60 cells showed increased expression of Nrf2, a key transcriptional regulator of the antioxidant response, and its target genes SOD2 and CAT. Conclusions The response to oxidative stress is heterogeneous in AML cells lines, and varies with expression of ARNT. ARNT activates expression of Nrf2, which stimulates expression of antioxidant genes resulting in an augmented adaptive response to ROS. Unexpectedly, ARNT also activates AKT signaling by repressing expression of the regulatory phosphatases PP2A and alpha4. These activities of ARNT result in increased resistance to the induction of apoptosis by TG, hydrogen peroxide, and chemotherapy. ARNT may play an important role in chemoresistance in and may be useful as a predictive or prognostic biomarker. Disclosures: No relevant conflicts of interest to declare.

Bone Marrow Stromal Cells Induce Bortezomib Resistance in Multiple Myeloma Cells through Downregulation of miRNA-101-3p Targeting Survivin

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1772-1772 ◽  
Author(s):  
Jahangir Abdi ◽  
Yijun Yang ◽  
Patrick Meyer-Erlach ◽  
Hong Chang
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Drug Resistance ◽  
Cell Lines ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Molecular Mechanisms ◽  
Marrow Stromal Cells ◽  
Survivin Gene ◽  
Induced Apoptosis

Abstract INTRODUCTION It is not yet fully understood how bone marrow microenvironment components especially bone marrow stromal cells (BMSCs) induce drug resistance in multiple myeloma (MM). This form of drug resistance has been suggested to pave the way for intrinsic (de novo) resistance to therapy in early stages of the disease and contribute to acquired drug resistance in the course of treatment. Hence, deciphering the molecular mechanisms involved in induction of above resistance will help identify potential therapeutic targets in MM combined treatments. Our previous work showed that BMSCs (normal and MM patient-derived) induced resistance to bortezomib (BTZ) compared with MM cells in the absence of stroma. This resistance was associated with modulation of a transcriptome in MM cells, including prominent upregulation of oncogenes c-FOS, BIRC5 (survivin) and CCND1. However; whether these oncogenes mediate BTZ resistance in the context of BMSCs through interaction with miRNAs is not known. METHODS Human myeloma cell lines, 8226, U266 and MM.1s, were co-cultured with MM patient-derived BMSCs or an immortalized normal human line (HS-5) in the presence of 5nM BTZ for 24 h. MM cell monocultures treated with 5nM BTZ were used as controls. Co-cultures were then applied to magnetic cell separation (EasySep, Stem Cell Technologies) to isolate MM cells for downstream analyses (western blotting and qPCR). Total RNA including miRNAs was isolated from MM cell pellets (QIAGEN miRNeasy kit), cDNAs were synthesized (QIAGEN miScript RT II kit) and applied to miScript miRNA PCR Array (SABioscience, MIHS-114ZA). After normalization of all extracted Ct values to 5 different housekeeping genes, fold changes in miRNA expression were analyzed in co-cultures compared to MM cell monocultures using the 2-ΔΔCt algorithm. Moreover, survivin gene was silenced in MM cells using Ambion® Silencer® Select siRNA and Lipofectamine RNAiMAX transfection reagent. Survivin-silenced cells were then seeded on BMSCs and exposed to BTZ. Percent apoptosis of gated CD138+ MM cells was determined using FACS. For our overexpression and 3'UTR reporter experiments, we transiently transfected MM cells with pre-miR-101-3p, scrambled miRNA or pEZX-3'UTR constructs using Endofectin reagent (all from GeneCopoeia). RESULTS BMSCs upregulated survivin gene / protein (a member of inhibitors of apoptosis family) and modulated an array of miRNAs in MM cells compared to MM cells in the absence of stroma. The more noticeably downregulated miRNAs were hsa-miR-101-3p, hsa-miR-29b-3p, hsa-miR-32-5p, hsa-miR-16-5p (4-30 fold) and highly upregulated ones included hsa-miR-221-3p, hsa-miR-409-3p, hsa-miR-193a-5p, hsa-miR-125a-5p (80-330 fold). We focused on miRNA-101-3p as it showed the highest level of downregulation (30 fold) and has been shown to function as an important tumor suppressor in other malignancies. Real time RT-PCR confirmed downregulation of miRNA-101-3p. Moreover, microRNA Data Integration Portal (mirDIP) identified miRNA-101-3p as a putative target for survivin and Luciferase activity assays confirmed binding of miRNA-101-3p to 3'UTR of survivin. In addition, overexpression of miRNA-101-3p downregulated survivin and sensitized MM cells to BTZ-induced apoptosis. Furthermore, silencing of survivin upregulated miRNA-101-3p and increased BTZ-induced apoptosis in MM cell lines both in the absence of BMSCs (Apoptosis range in BTZ-treated conditions: 57.65% ± 4.91 and 28.66% ± 0.78 for si-survivin and scrambled control, respectively, p<0.05) and in the presence of BMSCs (41.23% ± 1.43 and 14.8% ± 0.66, for si-survivin and scrambled control, respectively, p<0.05). CONCLUSION Our results indicate that BMSCs downregulated miRNA-101-3p and upregulated survivin in MM cells compared to MM cells in the absence of stroma. Silencing of survivin or overexpression of miRNA-101-3p sensitized MM cells to BTZ in the presence of BMSCs. These findings suggest that miRNA-101-3p mediates BTZ response of MM cells in the presence of BMSCs by targeting survivin and disclose a role of survivin-miRNA-101-3p axis in regulation of BMSCs-induced BTZ resistance in MM cells, thus provide a rationale to further investigate the anti-myeloma activity of miRNA-101-3p in combination with BTZ as a potential novel therapeutic strategy in MM. Disclosures No relevant conflicts of interest to declare.

Targeting mutant p53 with PK11007: A new approach for the treatment of patients with triple-negative breast cancer?

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e14099-e14099 ◽  
Author(s):  
Naoise C Synnott ◽  
Matthias R Bauer ◽  
Stephen F. Madden ◽  
Alyson M. Murray ◽  
Rut Klinger ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Cell Lines ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
P53 Protein ◽  
Mutant P53 ◽  
Inhibition Of Proliferation ◽  
Tnbc Cell ◽  
Induced Apoptosis

e14099 Background:The identification of a targeted therapy for patients with triple-negative breast cancer (TNBC) is one of the most urgent needs in breast cancer therapeutics. Since the p53 gene is mutated in approximately 80% of TNBC patients, it is a potential therapeutic target for this form of breast cancer. PK11007 is a 2-sulfonypyrimidine that stabilizes and reactivates mutant p53 (Bauer et al, PNAS 2016). The compound recently was reported to preferentially decrease viability in p53-compromised cancer cells. The aim of this investigation was to evaluate PK11007 as a potential new treatment for TNBC. Methods: Cell viability was determined using the MTT assay. Apoptosis was detected using Annexin V Apoptosis Detection Kit. Migration was determined by Transwell migration assay. Knockdowns of p53 protein were carried out using predesigned Flexitube sequences (Qiagen). Results: IC50 values for inhibition of proliferation by PK11007 in the panel of 17 breast cell lines ranged from 2.3 to 42.2 μM. There were significantly lower IC50values for TNBC than for non-TNBC cell lines (p = 0.03) and for p53-mutated cell lines compared with p53 WT cells (p = 0.003). Response to PK11007 however, was independent of ER or HER2 status of the cells. In addition, PK11007 induced apoptosis and inhibited migration in p53 mutant cell lines. Using RNAseq and gene ontogeny analysis, we found that PK11007 altered the expression of genes enriched in pathways involved in regulated cell death, regulation of apoptosis, signal transduction, protein refolding and locomotion. To establish if PK11007 acts by targeting mutant p53, we used siRNA to knockdown p53 in 3 p53-mutated TNBC cell lines. Reduction in p53 protein levels resulted in a significant decrease in the growth inhibitory effects of PK11007, in all 3 cell lines investigated, suggesting that PK11007 mediates growth inhibition via p53. The observations that PK11007 inhibited cell growth, induced apoptosis, blocked cell migration and altered genes involved in cell death, are all consistent with the ability of PK11007 to activate mutant p53. Conclusions: Based on our data, we conclude that targeting mutant p53 with PK11007 is a potential approach for treating p53-mutated TNBC.

scholarly journals Divergent Actions of Pyruvate and ATP in Glucose-mediated Irinotecan Chemoresistance in Colorectal Cancer

2021 ◽  
Author(s):  
Chung-Yen Huang ◽  
Yu-Chen Pai ◽  
Linda Chia-Hui Yu
Keyword(s):  
Colorectal Cancer ◽  
Cell Lines ◽  
High Glucose ◽  
Structural Damage ◽  
Topoisomerase I ◽  
Molecular Mechanisms ◽  
Flow Cytometric Analysis ◽  
Quiescent State ◽  
Altered Glucose ◽  
Induced Apoptosis

Abstract Background: Altered glucose metabolism is associated with chemoresistance in colorectal cancer (CRC). The aim of this study was to illustrate the molecular mechanisms of glucose-mediated chemoresistance against irinotecan, a topoisomerase I inhibitor, focusing on the distinct roles of metabolites such as pyruvate and ATP in modulating cell death and proliferation. Methods: Four human CRC cell lines, tumorspheres, and mouse xenograft models were treated with various doses of irinotecan in the presence of high concentrations of glucose, pyruvate or ATP-encapsulated liposomes. Cell apoptosis was measured by DNA fragmentation and caspase activities, and necroptosis was evaluated by immunoprecipitation of receptor-interacting protein kinase (RIP) 1/3 complex. Cell cycles were assessed by flow cytometric analysis.Results: Human CRC cell lines treated with irinotecan in the presence of high glucose displayed increased cell viability and larger xenograft tumor sizes in mouse models compared to those treated in the presence of normal glucose. Irinotecan induced apoptosis and necroptosis, both of which were mitigated by high glucose. Liposomal ATP prevented irinotecan-induced apoptosis, while it had no effect on necroptosis. In contrast, pyruvate attenuated the RIP1/3-dependent necroptosis via free radical scavenging, without modulating apoptotic levels. Regarding the cell cycle, liposomal ATP aggravated irinotecan-induced G0/G1 shift whereas pyruvate diminished the G0/G1 shift, showing opposite effects on proliferation. Last, tumorsphere structural damage, an index of solid tumor responsiveness to chemotherapy, was determined. Liposomal ATP increased tumorsphere sizes while pyruvate prevented the deformation of spheroid mass. Conclusions: Glucose metabolites confer tumor chemoresistance via multiple modes of action. Glycolytic pyruvate attenuated irinotecan-induced necroptosis and potentiated drug insensitivity by shifting cells from a proliferative to quiescent state. On the other hand, ATP decreased irinotecan-induced apoptosis and promoted active cell proliferation, which might contribute to tumor recurrence.

Suppression of MLL-AF4 by Small Interfering RNAs Inhibits Proliferation and Induces Apoptosis in T(4;11)-Positive SEM Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4433-4433
Author(s):  
Johann Greil ◽  
Maria Thomas ◽  
Christian Huenefeld ◽  
Hans-Peter Vornlocher ◽  
Philipp Hadwiger ◽  
...  
Keyword(s):  
Fusion Gene ◽  
Chromosomal Translocation ◽  
Fusion Transcript ◽  
Derivative Chromosome ◽  
Mrna Levels ◽  
Small Interfering Rnas ◽  
Chromosome 11 ◽  
Inhibition Of Proliferation ◽  
Treatment Concepts ◽  
Cell Cycle Transition

Abstract The reciprocal chromosomal translocation t(4;11)(q21;q23) creates the fusion genes MLL-AF4 and AF4-MLL located on derivative chromosome 11 or derivative chromosome 4, respectively. We used small interfering RNAs to suppress the MLL-AF4 fusion gene in the t(4;11)-positive leukaemic cell line SEM. Electroporation of SEM cells with MLL-AF4 siRNAs caused a more than two fold transient decrease in MLL-AF4 mRNA levels, which lasted for three days. The reduction in MLL-AF4 fusion transcript levels were associated with a severely diminished clonogenicity, inhibition of proliferation and of G1-S cell cycle transition and induction of apoptosis. Therefore, MLL-AF4 siRNAs are not only useful to study the functions of MLL-AF4 in leukaemogenesis, but may be also promising agents for novel treatment concepts for t(4;11)-associated leukaemias.

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